Liquid crystal panels used in liquid crystal display devices have a configuration in which a liquid crystal layer is sandwiched between a pair of glass substrates, of which one of the glass substrates is an array substrate including TFTs, which are switching elements, and pixel electrodes. The array substrate has a configuration in which gate wiring lines and source wiring lines are provided on the same substrate in a grid pattern, and a TFT and a pixel electrode are provided at the intersection of each gate wiring line and source wiring line. In a liquid crystal panel having such a configuration, the OFF characteristics of TFTs in recent years have been improving, and thus, electric charge stored in the pixel electrodes by the TFTs being charged is less susceptible to natural discharge. If the electric charge stored in the pixel electrode remains for a long period of time, this results in the risk of burn-in or flickering in the display screen. The technique disclosed in Patent Document 1 is known as to prevent burn-in and flickering in the display screen.